1. The Field of the Invention
The present invention relates generally to printed circuit boards for use in PC cards. More particularly, embodiments of the present invention relate to an improved chip component assembly which streamlines the manufacturing of the PC card while also utilizing relatively less space on the printed circuit board.
2. The Relevant Technology
The ever-increasing demand for personal computers and related equipment may be ascribed to any of a variety of factors. One such factor is that while the capabilities and performance of computers have improved dramatically in recent years, the average cost of computers has also declined during the same period. This divergence in cost and performance has been a significant factor in fueling the demand for personal computers.
Another factor driving the demand for personal computers is the expansion and development of the global computer network commonly known as the xe2x80x9cInternet,xe2x80x9d and related network communications. More and more commercial and non-commercial enterprises are conducting business by way of the Internet, and consumers need personal computers to gain access to the products and information that are available by way of the Internet.
Further, advances in the power and sophistication of computer application software, operating systems, communications software, and peripheral devices have required the development of computers with greater processing speeds and capacities. At the same time however, the pressure to at least maintain, and preferably reduce, the physical size of the computer and its various components has increased as well. Accordingly, downsizing and miniaturization of computer components is an issue of great importance in the industry.
Various efforts are currently underway to maintain, or expand, the power of personal computers and related peripheral devices, while at the same time reducing the size, or form factor, of such computers and devices. In one such effort, manufacturers began to develop miniature portable expansion devices, also known as xe2x80x9cPC cards,xe2x80x9d having smaller sizes. Examples of such PC cards include add-on memory cards, modems, network interface cards, and wireless communication cards. The typical PC card was designed to plug into a port, slot, or socket in the host computer. As a result, PC cards serve to expand the power and capability of the host computer without significantly increasing the size of the physical envelope of the host computer.
As suggested above, PC cards may take a variety of forms and embody a variety of different functionalities. As needs have emerged in the industry, different types of PC cards necessary to implement concepts responsive to those needs have been developed. By way of example, modem PC cards have been developed that are configured to facilitate communication between a host device, in which the modem PC card is received, and various remote devices, such as telephones, networked computers, and the like. Such modem PC cards have become popular due to their small size, relatively low cost, and their ability to interface directly with currently existing RJ-type communication plugs, such as are typically employed in the context of computer network applications.
Notwithstanding the foregoing useful features, various problems and shortcomings have conspired to impede advancement in the art. Many of such problems and shortcomings relate to the chip components typically employed in PC cards, and the related manufacturing and assembly processes.
Known PC cards typically employ a wide variety of components. One example of a component commonly used in PC cards is the so-called chip components. Chip components typically installed in PC cards may include, among other things, chip capacitors, chip inductors, chip resistors, and chip filters. Many known chip components have a body that is characterized by a geometry which includes relatively large opposed upper and lower surfaces, or edges, each of which may be square or rectangular, and four relatively smaller rectangular side surfaces interposed between the upper and lower surfaces. Because such chip components are typically mounted on a printed circuit board (PCB) in a way that the lower surface is arranged in a face-down orientation with respect to the PCB, at least two of the rectangular side surfaces typically have attached thereto respective terminal elements suitable for connecting with corresponding solder pads on the PCB. The terminal elements, in turn, are in electrical communication with various functional elements contained within the chip component.
During assembly, the chip component is mounted so that the respective terminal elements contact corresponding solder pads on the PCB. The chip component can then be permanently joined to the PCB by attaching the respective terminal elements to the appropriate solder pads by soldering. In many cases, the attachment of the chip component to the PCB is accomplished as part of an automated manufacturing process. As discussed in greater detail below however, the aforementioned chip component configurations and installation processes implicate at least one significant problem.
In particular, it is a consequence of typical chip component installation configurations that because the chip component is placed so that the relatively larger square face is oriented face down with respect to the top surface of the printed circuit board, the chip component necessarily takes up relatively more space on the PCB than if, for example, the chip component was mounted edgewise so that one of the relatively smaller rectangular edges was attached to the printed circuit board instead. In view of the demand for PC cards of increasing power and functionality, and the consequent emphasis on efficient use of the limited PCB surface area, such chip placement arrangements are undesirable because they unnecessarily occupy space on the PCB that could otherwise be used to accommodate the installation of additional components.
The foregoing problem is further aggravated by the fact that many of such chip components must be grounded to the printed circuit board and/or other structures in order to assure their continued effective operation and/or the safe and effective operation of the PC card and related devices and components. For example, it is frequently desired to ground chip components so as to preclude electrostatic discharge (ESD) and electro-magnetic interference (EMI) that can impair the functionality and operability of the PC card in which the chip components are installed.
As another example, in modem PC cards, a group of chip capacitors is commonly employed to provide the dual functions of providing a common alternating current (AC) reference between the modem and the telephone line to which the modem is connected, as well as capturing high frequency noise at the modem and returning the high frequency noise to ground before it can be transmitted down the telephone line. In order that they can effectively and reliably implement the aforementioned functionalities, the chip capacitors must be grounded.
Typically, the grounding of chip components, such as the chip capacitors discussed above, is accomplished through some type of grounding device that must be connected both to the chip component and to a ground pad on the PCB. As a consequence of such configurations, many known grounding devices act to further increase the amount of PCB space required to accommodate installation of the chip component. As noted above, such a result is at cross purposes with the overarching desire and need to maximize the functionality of PC cards.
In view of the foregoing problems, various attempts have been made to develop arrangements of chip components, and related grounding devices, directed toward facilitating more efficient use of the available space on the PCB. One technique commonly employed is the reorientation of the various chip components so that they are mounted on edge in the PCB in a so-called xe2x80x9ctombstonexe2x80x9d orientation. One benefit of such an arrangement is that, due to the relatively smaller xe2x80x9cfootprintxe2x80x9d of the edge of the chip component, as compared to the face of the chip component, relatively less space is required on the PCB to accommodate installation of the chip component and, accordingly, a greater number of chip components can be mounted in a given area on the PCB.
In an effort to improve the utility of such arrangements, xe2x80x9cbanks,xe2x80x9d or arrays, of chip components have been developed that include a plurality of chip components glued to each other by way of adhesive or the like. Because the individual chip components are glued to each other, such an array permits a plurality of chip components to be installed on the printed circuit board in a single operation. While known chip component arrays contribute to an increase in the efficiency with which PCB space is utilized, they nevertheless suffer from a variety of problems and shortcomings.
As noted above, the grounding of chip components is important for a variety of reasons. To those ends, known chip component arrays typically require one or more grounding devices. However, because such grounding devices must connect with a plurality of components in order to effectively ground all such components, many known grounding devices are typically relatively large and bulky components that occupy a relatively large portion of space inside the PC card and accordingly serve to preclude the installation of additional components that could otherwise be employed.
Furthermore, it is often the case that known grounding devices are installed by hand only after the chip component array has been secured to the printed circuit board. For example, in some arrangements, an xe2x80x9cSxe2x80x9d shaped grounding clip is employed that receives the edge of the PCB, so as to come into contact with a trace or ground pad on the PCB, and includes an extending portion which contacts the housing of the PC card, thereby grounding the PCB to the housing.
Due to the relatively large size of such grounding clips, and the limited precision with which a human can manipulate and assemble small devices such as PC cards and their component parts, the grounding pad on the PCB to which the grounding device must be attached is relatively large. The relatively large size of the grounding pad required by the grounding device acts as yet another limitation on the available space on the PCB and, accordingly, the efficiency with which such space is used.
Another problem associated with such known arrangements concerns associated manufacturing processes. In particular, such chip component array and grounding device arrangements typically implicate at least two installation steps. In the first step, the chip component array is placed on the PCB by one of a variety of well known technique assembly techniques, such as pick-and-place. However, because the grounding device is separate from the chip component array, an additional step is required to attach the grounding device to the chip component array and the PCB. As noted above, the inefficiency of the manufacturing process is further aggravated by the face that the grounding device typically is not placed by a machine but rather must be placed manually on the PCB.
Note that in situations where a chip component array is not employed, the efficiency of the assembly process is further impaired. In particular, each chip component must be placed in a separate operation on the PCB, and then a grounding device manually connected to the PCB and the separately placed chip components. Such processes tend to impair both the speed and the quality associated with the manufacturing of the PC card and accordingly contribute to an increase in the overall cost of the PC card.
Finally, it is frequently desirable to ground chip components both to the PCB as well as to another, ancillary, ground plane. Typically, such grounding has been achieved through the use of at least two separate grounding devices. However, the use of two grounding devices complicates the PC card assembly process and accordingly contributes to an overall increase in the cost of the PC card.
In view of the foregoing problems and shortcomings, and others with existing chip component arrangements and associated grounding devices, it would be an advancement in the art to provide a chip component assembly including an array of chip components oriented to minimize the overall footprint of the chip component assembly on a printed circuit board. Additionally, the chip component assembly should include a grounding device arranged to ground the chip component assembly to the PCB as well as to the housing of the PC card, and which requires only a relatively small ground pad on the PCB. Further, the chip component assembly should obviate the need for any manual steps in the construction of the chip component assembly and the placement of the chip component assembly on the PCB. Finally, the chip component assembly should be well suited for use in conjunction with pick-and-place manufacturing techniques.
The present invention has been developed in response to the current state of the art, and in particular, in response to these and other problems and needs that have not been fully or adequately resolved by currently available chip component assemblies. Thus, it is an overall object of embodiments of the present invention to provide a chip component assembly which includes an arrangement of chip components that promotes efficient use of the surface area of the PCB to which the chip component array is mounted, while also lending itself to use in conjunction with pick-and-place manufacturing processes, and which includes a grounding device that facilitates grounding of an array of chip components both to a PCB and a secondary ground plane.
Embodiments of the present invention are well suited for use in the context of PC cards and the like. However, it will be appreciated that embodiments of the present invention are suitable for use in any application or environment where it is desired to employ a chip component assembly that may be grounded to or contacting at least two different structures while at the same time maximizing the efficiency with which the surface area of a PCB is utilized, and which can be readily installed using pick-and-place manufacturing.
In one embodiment of the present invention, a chip component assembly is provided that includes a plurality of chip components, preferably capacitors, each having first and second terminal elements. An array ground plane, preferably comprising solder coated phosphor bronze, of the chip component assembly includes structure configured to receive, or otherwise cooperate with, the respective second terminal elements of the chip components and is soldered thereto so as to maintain the chip components in a desired arrangement with respect to each other and so that the array ground plane is electrically connected to the respective second terminal elements. Preferably, the chip components are arranged so that their respective first terminal elements can be joined to electronic circuitry of a printed circuit board.
The array ground plane additionally includes a grounding leg, preferably integral with the array ground plane, that physically and electrically connects the array ground plane to a grounding pad on the PCB to which the chip component assembly is mounted. Finally, the array ground plane includes a plurality of resilient contact elements which serve to establish and maintain substantial and continuous physical contact between the array ground plane and an adjacent ancillary ground plane when the chip component assembly is disposed inside the PC card. Preferably the ancillary ground plane comprises the electrically conductive upper cover of the PC card housing.
Due to the edge mounted, or xe2x80x9ctombstone,xe2x80x9d orientation of the chip components, the chip component assembly is effective in promoting a relatively more efficient use of available surface area on the PCB to which it is mounted. Further, the configuration and disposition of the array ground plane and ground path structure facilitates simultaneous grounding of the chip component assembly to the PCB as well as to the ancillary ground plane. Finally, because the chip component assembly is manufactured prior to placement on the printed circuit board, it is well suited for use in conjunction with pick-and-place manufacturing techniques and thus eliminates the costs typically associated with partial or complete manual assembly and placement.
In operation, the functionality of the chip component assembly is facilitated by the connections between the respective first and second terminal elements of the chip capacitors and the electronic circuitry on the printed circuit board. Any electrostatic charge buildup, or undesirable noise, in the chip component assembly is safely drained from the chip component assembly by way of the array ground plane and ground path structure. In one embodiment of the present invention, the chip component assembly serves to provide a common AC reference between a modem in the PC card and the telephone line to which the modem is connected.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.